Summary: Core A Core A is the Administrative Core for the Program Project. It includes two main aims: to provide administrative support and financial management support for the Projects and Cores. The administrative support includes organizing triweekly meetings of the Project and Core Leaders (the Executive Committee) and all PPG investigators. The Executive Committee addresses all issues related to scientific progress, plans for future meetings, and when necessary (in closed session) personnel issues. The meeting of all of the PPG investigators (including all of the workers associated with the PPG Projects or Cores in all labs that are involved) usually numbers about 25 people, and is a forum for presenting ongoing work on a regular, continuing basis. This allows comments and criticisms that refine the scientific approach and data analysis. The Administrative Core also organizes meetings of the Internal Advisory Board (on years 1, 3, and 5 of the PPG) and of the External Advisory Board (on years 2 and 4). The Internal Advisory Board, which will be chaired by Dr. Gene Nattie, who will also attend the tri- weekly meetings, will consist of local investigators with an interest in the science that is being done. They will also be invited to the External Advisory Board meetings, as participants. The External Advisory Board meetings will review progress, give advice on next steps, and help to refine the quality of the science in the PPG group. Financial administration under Core A will include providing monthly updates to investigators on their budgets, and helping with annual reports to the NIH. It will also report back to the Program Director who will track expenditures, and work with investigators who fall behind in their scientific work or exceed their budgets. Core A will provide necessary services to allow the Projects and Cores to work together smoothly and to achieve their Aims.